1. Field of the Invention
This invention relates to integrated devices for generating an output signal which is a function of flow rate of a fluid.
2. Description of the Prior Art
Various devices have been used heretofore to measure the flow in conduits of fluids, such as the flow of hydrocarbon liquids or gases in pipelines. However, such devices as have been used heretofore have either been quite bulky and expensive, requiring substantial monitoring and power supplies, or have not provided accurate monitoring of flow rate. Consequently, although such prior devices are of necessity in widespread use, they are, generally speaking, either expensive or inaccurate.
Linear variable differential transformers are well known and are shown, for example, in U.S. Pat. No. 3,600,669 and U.S. Pat. No. 3,848,180. Various physical embodiments of such transformers may be utilized, and various electronic circuits utilized to excite such transformers, as is shown in the aforementioned patents.
Bourdon tubes are also well known in the art. Helical type Bourdon tubes are described in U.S. Pat. No. 3,013,233, in which there is shown a pair of helical Bourdon tubes utilized to measure pressure differential. In U.S. Pat. No. 3,296,868, there is shown a device which utilizes a pair of Bourdon tubes in conjunction with a differential transformer in order to generate a signal which is a function of the pressure differential between the inlet pressures applied to the two Bourdon tubes.